A method is presented to draw rectangles to represent categorical data rela
tionships. The idea is an adaptation of a scaled Venn diagram. Rectangles a
re drawn with area proportional to the frequency of categories and the rect
angles are positioned to overlap each other so that the areas of overlap ar
e in proportion to the joint frequencies of the characteristics. The diagra
ms are especially useful to illustrate symptom co-occurrence. Copyright (C)
2001 John Wiley & Sons, Ltd.